CVE-2026-40880Network attack vector

Consensus split via height-blind verification cache

Published Apr 21, 2026 · Updated Apr 21, 2026

Improper transaction verification in Zebra before 4.3.1 and zebra-consensus before 5.0.2 allows attackers to cause a consensus split. The mempool cache skips height-dependent revalidation, so an ahead-of-tip block can reuse a transaction that is valid at H+1 but expired at H+2. Exploitation requires mining and ordering the two blocks; affected nodes accept the invalid block and fork from nodes that fully revalidate it.

CVSS severity7.2
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper transaction verification in Zebra before 4.3.1 and zebra-consensus before 5.0.2 allows attackers to cause a consensus split. The mempool cache skips height-dependent revalidation, so an ahead-of-tip block can reuse a transaction that is valid at H+1 but expired at H+2. Exploitation requires mining and ordering the two blocks; affected nodes accept the invalid block and fork from nodes that fully revalidate it.

The record

CVE
CVE-2026-40880
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
Zcash Foundation
Product
zebra-consensus
Classifications
CWE-1025, T1565.001
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 5.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Zcash Foundation · zebra-consensusversion=< 5.0.2
Zcash Foundation · Zebraversion=< 4.3.1

Published CVSS scores

8.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
7.2GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1025Comparison Using Wrong Factors
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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